Gender is a Major Contributor for Increased Tidal Volume Use in Intensive Care Unit A G Sankri-Tarbichi, MD1, S Ansari, MD1, M Zamlut, MD1, and A O Soubani, MD1. 1Wayne State University, Detroit, MI, United States. A G Sankari-Tarbichi, MD1,2, M Zamlut, MD2 and A O Soubani, MD1.2. 1Wayne State University; 2Detroit Medical Center, Detroit, MI, USA. ABSTRACT ABSTRACT ABSTRACT HYPOTHESES RESULTS Title: Gender and actual body weight are major contributors for increased tidal volume use in intensive care unit. A G Sankri-Tarbichi, MD1, A Ansari, MD1, M Zamlut, MD1 and A O Soubani1. 1Wyane State University, Detroit, MI, United States. Low tidal volume ventilation in acute lung injury and acute respiratory distress syndrome (ALI/ARDS) improves outcome. Organizational and clinician barriers to low tidal volume implementation are reported. Objective: To assess the compliance regarding the use of low tidal volume ventilation in ALI/ARDS in a single university hospital medical intensive care unit (MICU). Design: observational study of 95 consecutive adult patients admitted to MICU and treated with mechanical ventilator for >24hours (age 61±14yrs, 52 Females, body mass index 29±8). Measurements: Actual body weight, predicted body weight (PBW), body mass index (BMI), tidal volume (Vt), arterial blood gas, vital signs and ventilatory parameters. Results: 1. Vt was higher in females compared to males (8.9±1.8 vs. 7.5±1.2 ml/kg PBW, p<0.001) which was associated with increased end-inspiratory plateau pressure (19.0± 5.9 vs. 14.1± 4.8 cmH2O, p<0.001) 2. In 20 patients (11 males and 9 females) fulfilled the criteria for acute lung injury (ALI)/acute respiratory distress syndrome (ARDS), Vt was significantly higher in females compared to males (9.1 1.3 vs. 7.2± 0.8 ml/kg, p=0.001). 3. Obese patients (BMI 30, n=36) had higher Vt compared to non-obese (9.8 ±1.5 vs. 7.5± 1.8 ml/kg PBW). 4. Mortality rate at discharge was higher in females than in males (36% vs 29%) and in obese than in non-obese (34% vs. 25%). Conclusions: 1) Female gender and obesity are the main contributors for increased tidal volume in mechanically ventilated patients in general and in ALI/ARDS patients in particular. 2) The increased tidal volume in females and obese patients is associated with worse outcome. 3) System improvement in utilizing predicted body weight during mechanical ventilator initiation is needed to increase the implementation of low tidal volume ventilation.   1- Tidal volume is higher in females and obese patients relative to males and non-obese patients, respectively. 2- Increased tidal volume in acute lung injury is associated with increased mortality. Tidal volume and Plat pressure are higher in critically ill females than in males Design Prospective observational study in tertiary care medical ICU Measurements Actual body weight, predicted body weight (PBW), body mass index (BMI), tidal volume (Vt), arterial blood gas, vital signs, hemodynamic parameters, primary diagnosis for APACHE IV score, and ventilatory parameters/pressures. Acute lung injury (ALI) is defined if PO2/FiO2<300 and lung infiltrates without heart failure. Inclusion criteria: All adult patients aged 18 -89 yo who are admitted to intensive care unit e and mechanically ventilated. Exclusion criteria: Age <18 yo, severe anemia (Hgb <8), pregnancy, Methhemoglobulinemia, Carbon monoxide exposure or toxicity, and pigmented skin. Tidal volume is higher in females with ALI than in males Mortality is higher in females with ALI than in males INTRODUCTION RESULTS Males Females Obese Non-obese N=126 57 69 49 77 Age (yrs) 61.4 ±12 61.6 ±14 59.6 ±14 62.7 ± 13 BMI 28.1± 6 29.5 ±9 37.5 ± 6* 23.4 ± 4 Weight (kg) 87.6 ±22 77.8 ±27 106.5 ±17* 66.8 ± 14 PBW (kg) 74.8 ±10* 57.5 ±9 64.9 ±12 65.6 ± 14 APACHE IV 95.9 ± 27 100.8 ±26 96.6 ± 22 100.2 ±29 VT/kg (mL) 7.4 ± 1 8.5 ±2* 8.4 ±1§ 7.8 ± 2 ALI (%) 14 (25) 26(38)* 9(18) 15(20) Low tidal volume ventilation in acute lung injury and acute respiratory distress syndrome (ALI/ARDS) improves outcome. In critically ill patients, however, the implementation of low tidal volume policy has not been optimal. The recognition of contributing barriers to low tidal volume implementations is vital for improved outcome in critically ill patients. The impact of increased tidal volume on patients with increased risk of lung injury is not known. DISCUSSION Female gender is a major contributor to increased tidal volume use in critically ill patients. Tidal volume and mortality at discharge are higher in females than in males with acute lung injury. System improvement is needed to increase the implementation of low tidal volume ventilation. * p<0.05, § p=0.07